Large scale genome wide association studies have shown that a genetic variant located on chromosome 12 (at 12p11) has been associated with a reduced risk of breast cancer . This genetic locus is near the gene PTHLH (Parathyroid Hormone-like Hormone). This gene is implicated in mammary gland development and also in tumour metastasis to bone. The presence of a substitution of single nucleotide Adenine to Guanine (A à G) at this locus has been identified in the population in the West of Ireland, with the G allele shown to be protective and the A allele associated with increased risk. Our hypothesis is that the A allele also predisposes to the development of bone metastases. The aim of my study therefore is to examine the outcomes of patients with breast cancer, comparing those patients carrying the A allele to patients bearing the G variant. To date, the DNA of 1181 patients with breast cancer has been genotyped for this variant. I plan to carry out a chart review of all patients and record management and outcomes, specifically disease metastasis and survival. Disease outcomes will then be correlated with genotype.